Among image forming apparatuses such as a copying machine and a printer, there is an apparatus in which fuses are provided in various units to detect replacement of an image forming unit with a new image forming unit.
In a temperature fuse of a unit that is disconnected by heating due to first energization to a new unit, if the fuse is once disconnected and reheated and melted, it is likely that the fuse is likely to adhere again. In a current fuse that is disconnected if an electric current equal to or larger than a specified current is fed by first energization to a new unit, it is necessary to provide a blowing-out circuit having a large current capacity in order to disconnect the fuse.